Additional schema descriptions

The dataset .json annotations are great for dataloading, however it would be really helpful to have more meaningful description of the entries. For example in LTA task, what is a difference between:

'interval_{start|end}_{sec|frame}'

and

'action_clip_{start|end}_{sec|frame}'

Or similarly, how are the data such as

['annotations'][idx]['noun']

formatted.

This is a dummy example, but most tasks have somewhat ambiguous annotations whose meaning is only accessible through trial and error and analysing benchmark codes/submissions. It would be very helpful to have these descriptions in the schema definitions.